.contentWrap{
    border: 1px solid red;
    width: 500px;
    min-height: 300px;
    position: absolute;
    top: 50%;
    left: 50%;
    /* margin-left: -250px;
    margin-top: -150px; */
    transform: translate(-50%,-50%);
}

.mainWrap{
    position: relative;
    height: 600px
}